How to use the flooring calculator
Pick the flooring type and enter the room size. For laminate, vinyl plank and hardwood, choose the layout and enter the square feet per box from the carton; the calculator adds the waste for that layout and rounds up to whole boxes. For carpet, it works out how the room is cut from a roll: carpet comes in fixed widths, so you pay for the full width even when the room is narrower.
The formulas
plank boxes = area × (1 + waste) ÷ ft² per box, rounded up
carpet strips = ⌈room width ÷ roll width⌉ (laid along the longer side)
carpet bought (yd²) = strips × roll width × (room length + 0.5 ft trim) ÷ 9
Worked example: a 14 × 12 ft bedroom
- Area: 14 × 12 = 168 ft².
- Laminate, straight: 168 × 1.10 = 184.8 ft² ÷ 20 ft² per box = 9.24, so 10 boxes.
- Carpet on a 12 ft roll: the 12 ft width fits in one strip, cut 14.5 ft long with trim: 12 × 14.5 = 174 ft² = 19.3 yd².
Waste allowances
| Layout | Typical extra |
|---|---|
| Straight, rectangular room | 10% |
| Diagonal, or many closets and angles | 15% |
| Herringbone or chevron | 20% |
| Carpet | Depends on roll width and seams |
Measuring a room for flooring
- Measure wall to wall at floor level, ignoring baseboards, and round up to the next inch.
- Include closets and doorways where the new floor continues, and the area under appliances you'll move back.
- Split L-shaped rooms into rectangles and set "Rooms this size" to 1 for each, or use the square footage calculator to add them up first.
- Stairs are separate: each tread and riser is cut individually, so count them by the piece rather than by area.
Before you order
- Acclimate laminate and hardwood in the room for the time the maker specifies, often 48 hours or more.
- Check the subfloor is flat. Most floating floors allow only small dips over a few feet; fill low spots first.
- Leave expansion gaps at walls for floating floors, hidden by baseboard or quarter round.
- Plan transitions at doorways: thresholds, reducers and stair nosing are bought separately by the piece.
- Carpet seams should run toward the main light source and away from traffic lanes. Ask the installer to draw a seam diagram.
Questions people ask
How much extra flooring should I buy?
About 10% for laminate, vinyl plank or hardwood laid straight, 15% for diagonal layouts or rooms with many angles and closets, and up to 20% for herringbone. Keep the leftover boxes for repairs.
How many boxes of laminate do I need?
Divide the room's square footage plus waste by the square feet per box printed on the carton. A 14 × 12 ft room is 168 square feet; with 10% that's 184.8, so with 20 square foot boxes you need 10 boxes.
How is carpet sold?
By the square yard, cut from rolls usually 12 ft wide (some 15 ft). You pay for the full roll width, so a room 13 ft wide needs a 12 ft piece plus a seamed strip, and the offcut is waste. That's why carpet waste is higher than the room's area suggests.
How do I convert square feet to square yards for carpet?
Divide by 9. A 168 square foot room is 18.7 square yards, but because of roll width and trim you may pay for more.
Do I need underlayment for vinyl plank?
Many vinyl plank and laminate products have pad attached; adding a second pad can void the warranty. Others need a separate underlayment. Follow the flooring maker's instructions.
Sources and assumptions
- Square feet per box and roll widths come from the product. Waste of 10% (straight), 15% (diagonal) and 20% (herringbone) are common installer allowances, not standards.
- 1 square yard = 9 ft² (NIST Handbook 44, Appendix C)
Last reviewed 27 October 2026. Every formula on this page is checked against the worked example above in our automated tests. Found a problem? Tell us.